iommu/mediatek: Adjust device link when it is sub-common

For MM IOMMU, We always add device link between smi-common and IOMMU HW.
In mt8195, we add smi-sub-common. Thus, if the node is sub-common, we still
need find again to get smi-common, then do device link.

Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Link: https://lore.kernel.org/r/20220503071427.2285-19-yong.wu@mediatek.com


Signed-off-by: Joerg Roedel <jroedel@suse.de>